[3.13.y-ckt stable] Patch "USB: whiteheat: fix potential null-deref at probe" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    USB: whiteheat: fix potential null-deref at probe

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt28.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 28f76f92ab0a14342fb7f4f221038ff754151437 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan at kernel.org>
Date: Wed, 23 Sep 2015 11:41:42 -0700
Subject: USB: whiteheat: fix potential null-deref at probe

commit cbb4be652d374f64661137756b8f357a1827d6a4 upstream.

Fix potential null-pointer dereference at probe by making sure that the
required endpoints are present.

The whiteheat driver assumes there are at least five pairs of bulk
endpoints, of which the final pair is used for the "command port". An
attempt to bind to an interface with fewer bulk endpoints would
currently lead to an oops.

Fixes CVE-2015-5257.

Reported-by: Moein Ghasemzadeh <moein at istuary.com>
Signed-off-by: Johan Hovold <johan at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/usb/serial/whiteheat.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/usb/serial/whiteheat.c b/drivers/usb/serial/whiteheat.c
index cc5a430..69fec1a 100644
--- a/drivers/usb/serial/whiteheat.c
+++ b/drivers/usb/serial/whiteheat.c
@@ -81,6 +81,8 @@ static int  whiteheat_firmware_download(struct usb_serial *serial,
 static int  whiteheat_firmware_attach(struct usb_serial *serial);

 /* function prototypes for the Connect Tech WhiteHEAT serial converter */
+static int whiteheat_probe(struct usb_serial *serial,
+				const struct usb_device_id *id);
 static int  whiteheat_attach(struct usb_serial *serial);
 static void whiteheat_release(struct usb_serial *serial);
 static int  whiteheat_port_probe(struct usb_serial_port *port);
@@ -117,6 +119,7 @@ static struct usb_serial_driver whiteheat_device = {
 	.description =		"Connect Tech - WhiteHEAT",
 	.id_table =		id_table_std,
 	.num_ports =		4,
+	.probe =		whiteheat_probe,
 	.attach =		whiteheat_attach,
 	.release =		whiteheat_release,
 	.port_probe =		whiteheat_port_probe,
@@ -218,6 +221,34 @@ static int whiteheat_firmware_attach(struct usb_serial *serial)
 /*****************************************************************************
  * Connect Tech's White Heat serial driver functions
  *****************************************************************************/
+
+static int whiteheat_probe(struct usb_serial *serial,
+				const struct usb_device_id *id)
+{
+	struct usb_host_interface *iface_desc;
+	struct usb_endpoint_descriptor *endpoint;
+	size_t num_bulk_in = 0;
+	size_t num_bulk_out = 0;
+	size_t min_num_bulk;
+	unsigned int i;
+
+	iface_desc = serial->interface->cur_altsetting;
+
+	for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
+		endpoint = &iface_desc->endpoint[i].desc;
+		if (usb_endpoint_is_bulk_in(endpoint))
+			++num_bulk_in;
+		if (usb_endpoint_is_bulk_out(endpoint))
+			++num_bulk_out;
+	}
+
+	min_num_bulk = COMMAND_PORT + 1;
+	if (num_bulk_in < min_num_bulk || num_bulk_out < min_num_bulk)
+		return -ENODEV;
+
+	return 0;
+}
+
 static int whiteheat_attach(struct usb_serial *serial)
 {
 	struct usb_serial_port *command_port;
--
1.9.1